1. Field of the Invention
The invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device including a light-shielding tape.
2. Discussion of the Related Art
The liquid crystal display (LCD) devices are widely used for notebook computers, monitors, TV, and so on, because of their high contrast ratio and capability to display moving images. The LCD devices use optical anisotropy and polarization properties of liquid crystal molecules to display images.
The LCD devices require a liquid crystal panel including first and second substrates and a liquid crystal layer interposed therebetween. An arrangement of the liquid crystal molecules in the liquid crystal layer is changed by an electric field induced in the liquid crystal panel to control light transmissivity.
Generally, an additional light source is required because the liquid crystal panel is a non-emissive-type display device. Accordingly, a backlight unit is disposed under the liquid crystal panel. The LCD device displays images using light produced by the backlight unit and supplied to the liquid crystal panel.
A cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp and a light emitting diode (LED) can be used as a light source of the backlight unit. Among these light sources, the LEDs are widely used because of advantages in size, power consumption and reliability.
On the other hand, the backlight unit may be classified into a direct type and an edge type according to a position of the light source. In the edge type backlight unit, a light guide plate is disposed under a liquid crystal panel, and the light source is disposed at a side of the light guide plate. In the direct type backlight unit, the light source is disposed under the liquid crystal panel without the light guide panel.
The direct type backlight unit has an advantage in brightness, while the edge type backlight unit has advantages in weight and thickness.
FIG. 1 a cross-sectional view of the related art LCD device including the edge type backlight unit.
Referring to FIG. 1, the LCD device includes a liquid crystal panel 10, a backlight unit 20, a main frame 30, a bottom frame 50 and a top frame 40.
The liquid crystal panel 10 includes first and second substrates 12 and 14 facing each other and a liquid crystal layer (not shown) therebetween. First and second polarizing plates 19a and 19b for controlling the polarization direction of light, are respectively disposed at front and rear sides of the liquid crystal panel 10.
The backlight unit 20 is disposed at a rear side of the liquid crystal panel 10. The backlight unit 20 includes an LED assembly 29 arranged along a length direction of at least one edge of the main frame 30, a reflective sheet 25 of white or silver color on the bottom frame 50, a light guide plate 23 on the reflective sheet 25 and an optical sheet 21 on the light guide plate 23. The LED assembly 29 is positioned at one side of the light guide plate 23 and includes at least one LED 29a emitting white light and an LED printed circuit board (PCB) 29b where the LED 29a is disposed. The optical sheet 21 includes a plurality of sheets.
The LCD device further includes a light-shielding tape 60, i.e., a curtain tape, over an edge of the optical sheet 21. The light leakage in a non-display region is shielded by the light-shielding tape 60.
The liquid crystal panel 10 and the backlight unit 20 are combined using the main frame 30, which can prevent movement of the liquid crystal panel 10 and the backlight unit 20. The top frame 40 cover edges of the liquid crystal panel 10 and sides of the main frame 30, so the top frame 40 can support and protect of the edges of the liquid crystal panel 10 and sides of the main frame 30. The bottom frame 50 covers back edges of the main frame 30, so the bottom frame 50 is combined with the main frame 30 and the top frame 40 for modularization.
Recently, the applications for LCD devices have become broader, and requirements of less weight, small size and larger display area are increased. Particularly, it is desirable to reduce a non-display area while increasing the display area. In other words, an LCD device with a narrower bezel is desired.
To meet these requirements, a thickness of the top cover 40, the bottom frame 50 and the main frame 30 needs to be reduced. However, when a thickness of the main frame 30, e.g., a horizontal length of the main frame 30 in FIG. 1, is reduced, there is not enough area on the main frame 30 for attaching the light-shielding tape 60. As a result, misalignment of the light-shielding tape 60 occurs.
When misalignment of the light-shielding tape 60 occurs, the light-shielding tape 60 is exposed beyond the main frame 30 or the display area of the liquid crystal panel 10 is shielded by the light-shielding tape 60. Additionally, a problem of light leaking at a boundary between the non-display area and the display area may occur. As a result, there are disadvantages in the brightness and the display quality.